Carborundum article.



UNITED STATES PATENT OFFICE.

FRANCIS A. J. FITZGERALD, OF NIAGARA FALLS, NEIV YORK.

CARBORUNDUM ARTICLE.

SPECIFICATION forming part of Letters Patent No. 650,235, dated May 22, 1900.

Original application filed August 7, 1899, Serial No. 726,472. Divided and this application filed September 25, 1899. Serial No. 731,545. (Specimens) To all whom it may concern:

Be it known that I, FRANCIS A. J. FITZGER- ALD, of Niagara Falls, in the county of N iagara and State of New York, have invented a new and useful Improvement in Carborundum Articles, of which the following is a full, clear, and exact description.

Although it frequently happens that carborundum-carbid of silicon-as made in the electric furnace is found in masses whose crystals are held together with more or less strength or firmness of cohesion, such masses have not been su'fficiently solid to permit of use in the arts without first separating the loosely-held grains, cementing them or binding them together with clay or like bond, and firing the same. The necessity for this is apparent when it is considered that of the original mixture used in the manufacture of carborundum over sixty per cent. is driven off as gas or vapor, and as the carborundum crystals occupy approximately the same space as the original mixture and have a higher specific gravity it follows that the masses are necessarily porous and loosely knit together. The bond of clay is sometimes objectionable and detracts from the value of the molded articles-as, for example, when the articles are to be exposed to a temperature sufficient to destroy the binding material.

In making my improved article of manufacture I press the grains or powder of carborundum of suitable size into the shape desired, which may be the shape of a finished article, and I may employ for such purpose any adhesive material which will hold the grains together even temporarily. For example, the grains may be mixed with a dilute solution of glue and then pressed into shape. The mass so molded is then heated in an electric furnace to or about the temperature originally used to produce the carborundum, and when so treated I have discovered that the carborunduin. will rccrystallize and will produce a veryhard dense mass, occupying substantially the same space into which it was compressed and without sub stantial loss of material by vaporization in such treatment,except the volatilizing of the material which may have been employed as a temporary bond. I may make in this way refractory bricks orcrucibles composed when finished of practically nothing but carborun= dum, or I may treat, as above described, carborundum articles molded into shape suitable for purposes of abrasion.

Where it is desired that the molded car borund um article should be an electrical conduotor, I may mix a conductor of electricity with the crystals, and I prefer to use graphite for such purpose, adding it preferably in the proportion of fifteen to twenty parts of graphite to eighty-five to eighty parts of carborundum; but these proportions may be Varied to any extent desired. When so mixed with graphite, the carborundum becomes a conductor of electricity and may be molded into crucibles, which may be heated by passing an electric current through them. In a separate patent application, Serial No. 726,472, I claim the method of making the article herein described. This present application is a division of the application just mentioned.

I claim-- 1. As a new article of man ufacture, a dense coherent recrystallized body of carborun dum; substantially as described.

2. As a new article of manufacture,a dense coherent recrystallized body of carborundum mixed with graphite; substantially as described.

In testimony whereof Ihave hereunto set my hand.

FRANCIS A. J. FITZGERALD.

Witnesses:

J. O. RICO, Jr., P. M. N. BENNIE. 

